1. Field of the Invention
The present invention relates to a monolithic ceramic capacitor, which is a type of capacitor element and which includes a dielectric layer including a ceramic dielectric material.
2. Description of the Related Art
A capacitor element generally includes an element body, in which conductor layers and dielectric layers are alternately stacked, and an outer electrode provided on an outer surface of the element body. The monolithic ceramic capacitor is a type of capacitor element, in which the dielectric layers include a ceramic dielectric material.
The monolithic ceramic capacitor typically includes therein a substantially rectangular-parallelepiped-shaped multilayer portion, in which a plurality of conductor layers serving as inner electrode layers and a plurality of ceramic dielectric layers are alternately densely stacked. The multilayer portion is covered with an outer layer portion formed of ceramic dielectric layers, and an extension layer portion, in which a relatively small number of the conductor layers are included as an extension portion in the ceramic dielectric layers. Thus, the above-described element body is formed.
To increase the capacity of the monolithic ceramic capacitor, it is required to increase the facing area between adjacent conductor layers included in the multilayer portion. To increase the facing area, it is effective to increase the density of the conductor material of a portion in which the conductor layers are arranged (so-called inner electrode density). Accordingly, continuity of the conductor layers is increased, the above-described facing area is increased, and thus the capacity of the monolithic ceramic capacitor is increased.
For example, Japanese Unexamined Patent Application Publication No. 2013-12418 discloses a monolithic ceramic capacitor with the increased continuity of the conductor layers.
However, when the continuity of the conductor layers is increased, delamination likely occurs. The delamination is a separation phenomenon occurring because of a large difference between likelihood of contraction of the conductor layer and likelihood of contraction of the ceramic dielectric layer. When thermal history is added, the thermal history acts as a shear force at a boundary portion between the ceramic dielectric layer and the conductor layer.
In particular, the delamination more likely occurs between the multilayer portion, in which the conductor layers and the ceramic dielectric layers are densely stacked, and the above-described outer layer portion. The delamination may cause a decrease in reliability as a product, and may cause a decrease in yield in a manufacturing process.
For example, the manufacturing flow of the monolithic ceramic capacitor typically includes metal-plating processing, which is processing of forming the outer electrode. In the metal-plating processing, the element body is immersed in solder liquid. At this time, if the delamination is occurring, adhesion between the dielectric layer and the conductor layer is insufficient, and the solder liquid enters an inner side portion of the element body through the portion in which the delamination is occurring. Consequently, the insulation resistance value between the conductor layers, the insulation of which should be sufficiently kept, is decreased, and hence the reliability may be decreased and the yield may be decreased.